Connecting RPM lead on a dyno on a C14?

[Rhino]

Went to have my bike dyno'ed this weekend. Found the 4 leeds from the ECU to the spark coils. W/G, W/R, W/Y and W/Blue. But was not able to get an RPM reading from any of them. Have read that the best place is the lead going into each coil but what a PITA. Any advice on the best place to connect the sensor lead from a dyno without pulling a bunch of plastic? We had 2 2010 C14's and couldn't get it to work on either bike. No problem on other bikes, a Honda RC-51 and a couple of BMW S1000's so I don't think it was the dyno.

[B.D.F.]

Any one of those wires should have done it. The dyno is probably looking for a voltage spike, called the 'fly back' voltage from the coil but there is not one of those from the C-14 coils. As far as tapping the high voltage, there is none of that either as the Coil- On- Plug system the C-14 uses has NO high voltage side available. This is a pretty sophisticated system and older testing devices just will not work with it (like an induction tachometer, for example). You may be up against the same thing.

Brian

Went to have my bike dyno'ed this weekend. Found the 4 leeds from the ECU to the spark coils. W/G, W/R, W/Y and W/Blue. But was not able to get an RPM reading from any of them. Have read that the best place is the lead going into each coil but what a PITA. Any advice on the best place to connect the sensor lead from a dyno without pulling a bunch of plastic? We had 2 2010 C14's and couldn't get it to work on either bike. No problem on other bikes, a Honda RC-51 and a couple of BMW S1000's so I don't think it was the dyno.

[Rhino]

Bummer, I was afraid of that. Don Guhl told TEXREX he is able to use those leads but I guess he has a newer/more sensitive dyno. I wonder if there is a work abound. If I had a chart showing the ratio of the engine rpm to speed for each gear why couldn't the dyno know the engine rpm from the rear wheel speed? I would think the pc software would have that function built in as an option. But I have little experience using a dyno.

[B.D.F.]

Certainly a fly- back could be built and isolated but that is a significant amount of work. As you say, I am sure there is a retrofit device for the dyno that will read logic- level signals as they are becoming the norm on motorcycles and we will be seeing much MORE of this, not less. The bad old days are not gone but they are on the move at least :-) COP systems are the way to go and the best system I know of and it is a great situation that more high- end bikes come with them.

You are also right about backing out the RPM mechanically but it is not that easy- not only does the gearing have to be known, the rear tire diameter would have to be measured also. Of course once you have the dyno chart with the ground speed on the X- axis, and you know what gear was used, you could do the conversion and jot that down on the graph manually. Probably the easiest, fastest way to do it and you can find the relationship between engine RPM and vehicle speed just by riding the bike and noting the speed at a given RPM, hopefully with a GPS as the speedo is inaccurate.

Brian

Bummer, I was afraid of that. Don Guhl told TEXREX he is able to use those leads but I guess he has a newer/more sensitive dyno. I wonder if there is a work abound. If I had a chart showing the ratio of the engine rpm to speed for each gear why couldn't the dyno know the engine rpm from the rear wheel speed? I would think the pc software would have that function built in as an option. But I have little experience using a dyno.

[Rhino]

Certainly a fly- back could be built and isolated but that is a significant amount of work. As you say, I am sure there is a retrofit device for the dyno that will read logic- level signals as they are becoming the norm on motorcycles and we will be seeing much MORE of this, not less. The bad old days are not gone but they are on the move at least :-) COP systems are the way to go and the best system I know of and it is a great situation that more high- end bikes come with them.

You are also right about backing out the RPM mechanically but it is not that easy- not only does the gearing have to be known, the rear tire diameter would have to be measured also. Of course once you have the dyno chart with the ground speed on the X- axis, and you know what gear was used, you could do the conversion and jot that down on the graph manually. Probably the easiest, fastest way to do it and you can find the relationship between engine RPM and vehicle speed just by riding the bike and noting the speed at a given RPM, hopefully with a GPS as the speedo is inaccurate.

Brian

Thats what I was thinking. Mount the GPS ride at exactly 60mph and note the rpm in 3-6 gears. But wouldn't the dyno software need to be able to do the mapping from this information to graph a torque curve? Or can it graph torque and HP over speed? If so, your right, I can annotate my own RPM on the graph.

[Richard. Wales UK]

Hi

How does the bike RPM meter get is signal?

Richard

[martin_14]

Thats what I was thinking. Mount the GPS ride at exactly 60mph and note the rpm in 3-6 gears. But wouldn't the dyno software need to be able to do the mapping from this information to graph a torque curve? Or can it graph torque and HP over speed? If so, your right, I can annotate my own RPM on the graph.

I did exactly that (but also in 1st and 2nd gear) and made a pretty accurate Excel table taking into account parameters like nominal wheel size, wheel radius correction, etc. I can send it to you if you want. Will save you quite a bit of field work.

[Rembrant]

I suspect most tuners are using Dynojet dynos, and they're tuning C14's with Power Commanders installed. Even if you were doing ECU tuning and had no intention of installing a PC5 permanently, you could still install one with a zero map for dyno tuning....wouldn't take all that long.

I bet that's what a lot of these guys are doing.

Rem

[Rhino]

I did exactly that (but also in 1st and 2nd gear) and made a pretty accurate Excel table taking into account parameters like nominal wheel size, wheel radius correction, etc. I can send it to you if you want. Will save you quite a bit of field work.

Excellent! Thank you Martin! PM on the way.

[Rhino]

I suspect most tuners are using Dynojet dynos, and they're tuning C14's with Power Commanders installed. Even if you were doing ECU tuning and had no intention of installing a PC5 permanently, you could still install one with a zero map for dyno tuning....wouldn't take all that long.

I bet that's what a lot of these guys are doing.

Rem

Interesting idea. I have the Ghul re-flash and haven't used a power commander. If the dyno is a Dynojet then it can interface directly with the Power Commander?

[Deziner]

When magazines dyno test bikes, do they remove all of the bodywork necessary to get to the coils?

[Rhino]

When magazines dyno test bikes, do they remove all of the bodywork necessary to get to the coils?

Most bikes you don't have to. We saw 5 or 6 bikes get dyno'ed and our C14's were the only ones with this problem.

The real problem is that he said he could plot HP but could not get torque without the RPM lead working. Why can't
he get torque relative to speed?

[gPink]

First I know nothing, but I thought torque was measurable and horsepower was an extrapolated number.

[Rhino]

First I know nothing, but I thought torque was measurable and horsepower was an extrapolated number.

Exactly! You apply a load, measure torque (the actual force) and extrapolate HP based on how fast the rpm/speed changes. But WTH do I know?

[Deziner]

I'm like Sgt Schultz,  I know nothing! But I'm pretty sure I've read magazine reviews about the C14 and they claim to have dyno tested them. Not like a magazine would ever "mis-remember"  actually doing a dyno test....

[Rhino]

I'm like Sgt Schultz,  I know nothing! But I'm pretty sure I've read magazine reviews about the C14 and they claim to have dyno tested them. Not like a magazine would ever "mis-remember"  actually doing a dyno test....

No doubt. But I think Brian is correct, needs a newer dyno/rpm sensor. As I said, Don Guhl told TEXREX2 he does it from the coil leads coming out of the ECU. So I think its just that the dyno we tried last Saturday had an older sensor that requires a higher energy signal. Just looking for a work around other than finding another dyno.

[MAN OF BLUES]

what does the Rostra cruise control utilize to sense RPM?
iirc the first installs required and adaptive "plug n play" inline harness adapter to the #1 stick coil, for rpm sensing... no?
I know we are using splicing on the speedo cable currently, but wayyyy back I thought there was a harness adapter that saved splicing into the stick coil leads...

[B.D.F.]

A coil wire was used to sense engine RPM but it never worked right- same basic problem as I suspect the dyno is having, no fly-back voltage. The newer method is the NSS tied in with the clutch and that one ain't too hot either- it works most of the time but not ALL the time....

The Rostra installs have always used the VSS as the main input to close the loop and govern throttle position. The engine RPM sensor was never more than the second 'safety net' method of disconnect, never the main input.

And I say this because as far as I know, I pioneered the install of the Rostra on the C-14. In fact I introduced the unit (the Rostra) to the 'other guy' (you know exactly who I mean Rich  ) on the other forum- he was using an Audiovox and having the usual vacuum / speed loss problem when I documented the install of a Rostra- he had never heard of them. The installation of a Rostra cured his problem too, at least the one involving the speed maintenance of a C-14 on the highway. :-)

Brian

what does the Rostra cruise control utilize to sense RPM?
iirc the first installs required and adaptive "plug n play" inline harness adapter to the #1 stick coil, for rpm sensing... no?
I know we are using splicing on the speedo cable currently, but wayyyy back I thought there was a harness adapter that saved splicing into the stick coil leads...